Buy the best house possible with little to no maintenance requirements (brick/aluminium windows...). The better the address the better the tenant. Buying outside of Auckland is probably advisable.

Expect capital gains to be moderate to flat in the near term. With current climate it may be beneficial to build.

Thoroughly vet prospective tenants. Every single one has the ability to destroy your asset. The fairer the rent, the more selective you can be. i.e. high rents attract desperate people.

Too much capital in a property is dead money. If you don't think you'll see 30% improvement per annum on your capital outlay then I'd say it's probably not worth the hassle and you'd be better off investing elsewhere. Remember that it can be time consuming. You need a return on your capital and your time.

The land agent will take far more than their fair share.